I've been a big fan of FreeBSD since I first acquired 4.4 on 4 CDs. By that point, I had already spent a lot of time in Linux, but I was always put off by its instability and inconsistency. Once I had FreeBSD installed, it felt like a dream. Everything worked the way it was supposed to, and the consistency of its design meant even older documentation would be mostly applicable without having to figure out how my system was different. There is a reason why in the early days of the Internet, a huge portion of servers ran FreeBSD.

But, that was a while ago. Since then, Linux has matured greatly and has garnered a lot of momentum, becoming the dominant Unix platform. FreeBSD certainly hasn't stood still, however. The FreeBSD team has kept current with hardware support, new features, and a modern, performant design.

"Well, GNU/Linux has a lot of hardware drivers but all these drivers are quality drivers?"

Mileage varies. Drivers that are problematic (in my experience) have been for the desktop (video/sound) or those for consumer devices that are added to the machine without researching linux compatibility (I was given a doxie scanner as a gift, but company behind it has said they would never support linux or release the specs, they've pulled the statement due to criticism but their policy is effectively unchanged).

On the other hand for a server I think you'd be hard pressed to find a server that linux doesn't work with even if you buy it at random. Some of the userspace components may be trickier to get without manufacturer support (ie raid monitoring/management).

"And do you really need that exotic controller on you mission critical server?"

Raid controllers are not really exotic on performance servers, and yes we do need it if we don't want to give up features like battery backup write back caching and hotswap, RAID offloading. With this you can commit transactions at tremendously high speeds even with RAID6. The backplanes in servers are often hardwired for the raid controller so you cannot really bypass them.

Don't confuse this with the "soft" raid that comes with low/mid machines.